10.1021/jo00304a024
The research focuses on the stereocontrolled total syntheses of penicillanic acid S,S-dioxide (10) and 6-aminopenicillanic acid (26) derived from (S)-aspartic acid and (R,R)-tartaric acid, respectively. The study's key steps involve the preparation and cyclization of nitroalkenes 8 and 23, with the reaction of these compounds with tetrabutylammonium fluoride followed by ozone and DBU yielding the bicyclic P-lactams 9 and 24, which are then transformed into the target penicillanic acid derivatives 10 and 26. The research concludes that (benzyloxy)nitromethane is a highly useful reagent in β-lactam chemistry, and the nitroalkene ring closure strategy is efficient and effective for preparing polyfunctional bicyclic β-lactams, with potential general applicability for constructing novel β-lactam systems.
10.1134/S1070428007120123
D. M. Musatov et al. detail a method for separating the enantiomers of tetrahydrofurfurylamine on a preparative scale using fractional crystallization of diastereoisomeric salts with natural L-tartaric acid. Tetrahydrofurfurylamine is a significant compound used in the synthesis of various medical agents, including diuretics, enzyme inhibitors, analgesics, neurotropic drugs, and anticarcinogenic agents. The study reports the isolation of (R)-tetrahydrofurfurylamine with a yield of 68% and an optical purity of over 98.5% as determined by HPLC. The separation process involved dissolving L-tartaric acid and racemic tetrahydrofurfurylamine in a mixture of water and acetone, followed by crystallization and recrystallization steps. The (R)-enantiomer was obtained with high purity, while the mother liquor yielded the (S)-enantiomer with 79% enantiomeric purity.
10.1055/s-0028-1087950
The research presents the synthesis of novel chiral ionic liquids (CILs) based on L-(+)-tartaric acid, leveraging its low cost and renewability as a chiral pool source. The study's main content involves a two-step synthesis strategy: first, reacting L-tartaric acid with benzylamine to form pyrrolidindione, followed by reduction with LiAlH4 to obtain benzylpyrrolidine. Subsequent quaternization with benzyl or n-dodecyl bromide under conventional or microwave heating yielded the desired chiral pyrrolidinium salts. The synthesized compounds were characterized by their melting points, and anion exchange was performed to obtain different ionic liquids. The researchers also examined the crystallographic structures of selected compounds to understand the absence of hydrogen-bonding interactions between cations, which contributed to the reduced melting points. The chiral recognition ability of these ionic materials was evaluated through NMR spectroscopy, observing the interaction between the synthesized cations and Mosher acid anion, which indicated the formation of diastereomeric salts. This research provides a foundation for further investigation into the potential of these CILs as solvents, catalysts, or ligands in asymmetric synthesis.
10.1016/0008-6215(86)85018-2
The research discusses a novel approach to synthesizing natural compounds containing α,β-unsaturated δ-lactones using carbohydrate precursors. The purpose of this study was to develop chiral synthons with the L configuration, which are essential for the enantiospecific synthesis of these compounds. The researchers successfully prepared 2,3-dideoxy-4,6,7,8-tetra-O-methyl-D-glycero-D-galacto-2-enono-1,5-lactone (1) through a series of chemical reactions starting from L-tartaric acid. Key chemicals used in the process included ethanethiol-hydrochloric acid, sodium hydride, methyl iodide, mercury(II) oxide-mercury(II) chloride, palladium on carbon catalyst, and toluene-p-sulphonic acid. The synthesis involved several steps, such as the preparation of 3-O-benzyl-D-glucose diethyl dithioacetal, its methylation, transacetalization, catalytic hydrogelation, and finally, the Wittig reaction to obtain the desired lactone. The study concluded with the successful preparation of the target lactone and the observation that the extension of these sequences for the preparation of other lactones with extended chains is feasible and under investigation.
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